A tiny zircon crystal found on a sheep ranch in Western Australia has been dated to 4.4 billion years ago, making it the oldest known piece of our planet. The discovery of this oldest rock indicates that the Earth’s crust formed just relatively soon after the planet itself formed – only 160 million years after the formation of the solar system.
The study was conducted by an international team lead by University of Wisconsin-Madison geoscience Professor John Valley and published in the journal Natural Geoscience.
The gem’s age was confirmed using two different methods, the widely used method that measured the radioactive decay of uranium to lead in a mineral sample and a new method known as atom-probe tomography that was able to identify individual atoms of lead in the crystal and determine their mass.
According to Valley, the findings support the “cool early Earth” theory that hypothesized that the Earth’s temperature was low enough to support liquid water and oceans shortly after the Earth’s crust solidified.
“This may also help us understand how other habitable planets would form,” added Valley.
Source: The Sydney Morning Herald
